The present invention generally relates to water flow control apparatus and, in illustrated embodiments thereof, more particularly relates to specially designed water heater convective heat trap constructions.
Water heaters of both the fuel-fired and electrically heated types typically have a tank portion in which pressurized, heated water is stored for on-demand delivery to various types of hot water-utilizing plumbing fixtures such as, for example, sinks, bath tubs and dishwashers. During standby periods in which discharge of stored hot water from the tank is not required, it is desirable to substantially reduce heat loss from the stored hot water to cooler areas outside the tank. For this reason it is customary practice to externally insulate the tank.
While this technique is effective in reducing undesirable heat loss from the tank body, stored water heat may also be lost by thermal convection flow of heated water from the tank through its cold water inlet and hot water outlet openings to piping connected thereto. In order to minimize this convective heat loss, various convective heat trap devices have been previously proposed for connection to the tank at or adjacent these inlet and outlet openings. These heat trap devices are basically check valve-type structures which freely permit water to flow through the tank inlet and outlet in operational directions during water supply periods, but substantially inhibit convective water outflow through the inlet and outlet during non-demand storage periods of the water heater.
One common type of convective heat trap utilizes a movable ball to block or impede undesirable convective water flow through its associated water inlet or outlet opening in the tank. While this ball type of heat trap typically eliminates or at least substantially reduces outward convective water flow, it also is prone to create undesirable noise (namely, xe2x80x9crattlingxe2x80x9d) during its operation. This has led to many complaints from water heater purchasers over the Years and corresponding repair or replacement costs for water heater manufacturers.
In response to this well-known problem typically associated with ball-type heat traps various xe2x80x9cflapperxe2x80x9d type heat trap constructions have been previously proposed as alternatives to movable ball-type heat traps. In this design, a flexible blocking member (or xe2x80x9cflapperxe2x80x9d) is appropriately positioned in each path of potential convective outflow currents of water from the tank (i.e., at or adjacent the cold water inlet and hot water outlet of the tank) and serves as a barrier to undesirable convective outflows of heated tank water during non-demand periods of the water heater. However, when one or more of the plumbing fixtures connected to the water heater is operated to draw hot water from the tank, the flappers resiliently deflect to freely permit cold water supply to the tank and hot water discharge from the tank. Because of the resilient nature of the flappers their operation is typically silent.
However, compared to ball type heat traps flapper type convective heat traps present their own types of problems, limitations and disadvantages including potentially higher cost and greater complexity, installation difficulties, additional shipping volume and less than optimal reductions in convective heat loss from their associated water heater. A need accordingly exists for improved water heater convective heat trap designs. it is to this need that the present invention is directed.
In carrying out principles of the present invention, in accordance with an illustrated embodiment thereof, a water heater is provided which includes a tank adapted to store a quantity of water and having water inlet and outlet openings; heating apparatus for heating water stored within the tank; and first and second specially designed heat traps respectively associated with the water inlet and outlet openings and operative to inhibit convective water outflows therethrough.
Each heat trap includes a tubular body extending along an axis; and first and second axially spaced apart resilient flapper structures carried by the body and having axially deflectable portions transversely extending across the interior of the body. Preferably, the deflectable flapper structure portions in each heat trap body are axially deflectable about circumferentially offset hinge locations adjacent the interior side surface of the body. Representatively, the hinge locations are circumferentially offset from one another by about 180 degrees. Additionally, when the resilient flapper portions are in undeflected orientations within their associated heat trap body they preferably define circumferentially extending gaps with the interior side surface of the body.
In an illustrated embodiment of the heat traps, each tubular body representatively has an outwardly projecting integral end flange with a noncircular driving recess formed in an outer side thereof. Axially spaced exterior annular grooves are formed in the body side wall, with circumferentially offset slots extending radially through the body at such grooves. Each resilient flapper member has a circular outer ring portion received in one of the grooves, and a generally circular interior portion received within the interior of the body and connected to the ring by a hinge tab portion extending outwardly through the associated slot and being formed integrally with the outer ring.
The heat trap at the cold water inlet of the tank is coaxially received in an upper end portion of a cold water inlet dip tube extending downwardly into the interior of the tank. Alternatively, the tubular body of the heat trap at the cold water inlet of the tank is eliminated, and the flapper members are incorporated directly into the dip tube to form a combination dip tube/heat trap structure.
Representatively, tubular connection spuds are externally secured to the tank over its cold water inlet and hot water outlet openings, and dip cup members extend downwardly through these openings. Tubular seal members circumscribe the hot water side heat trap body and the dip tube and sealingly engage the associated spuds and dip cups. Illustratively, these external seal structures are separate elements, but may alternately be formed integrally with the internal flapper portions. The non circular driving recesses in the flange portions of the heat traps are used to thread the flange edges into threaded interior portions of the connection spuds.
The specially designed neat traps substantially inhibit undesirable convective water flow outwardly through the cold water and hot water tank openings, with the circumferentially offset, axially spaced interior flapper portions forcing tank water to take a generally serpentine path outwardly through the traps. The heat traps operate very quietly, are of a simple construction, are easy to install, are inexpensive to manufacture, and operate in a reliable manner to materially reduce undesirable convective outflow of water from the tank during standby periods of the water heater.